1. Field of the Invention
One embodiment of the present invention relates to a thin film transistor and a fabrication method thereof.
2. Description of the Related Art
In recent years, a thin film transistor (TFT) over a substrate having an insulating surface (e.g., a glass substrate) has been attracting attention. TFTs are widely used for integrated circuits (ICs) and electronic devices such as electro-optical devices. In an image display device such as a liquid crystal display device, a TFT formed using an amorphous semiconductor or a polycrystalline semiconductor is mainly used as a switching element.
In contrast, a TFT formed using a microcrystalline semiconductor for the channel formation region has been actively developed in recent years. For example, Patent Document 1 and Patent Document 2 disclose techniques for controlling nucleation positions and nucleation density in a microcrystalline semiconductor film.